Antiknock fuel



Patented Mar. 28, 1933 UNITED STATES FRANK I. BUSGH, OF ERIE, PENNSYLVANIA ANTIKNOCK FnEL No Drawing. Application filed July 15,

My invention relates to anti-knock fuel, that is to say, a mixture containing gasoline which is suitable for use in high compression explosion engines. My new fuel comprises a mixture of gasoline and para-cymene.

Para-cymene is present in large quantities in sulfite spruce and balsam turpentine which is a by-product of the sulfite Wood pulp industry, for which no large industrial use has been found heretofore. This turpentine may be submitted to distillation with superheated steam in an apparatus arranged to permit the vapors to pass through a 10-25% solution of sodium carbonate or other suitable alkali solution, and then into the condenser, the solution serving to neutralize any acid which might be carried along with the vapors. The oil may be separated from the distillate by means of a separatory funnel, dried over calcium chloride and then fractionated. The fraction which distils off at 17 5180 C. consists' of, or contains, the bulk of the paracymene present in the turpentine.

To four parts by volume of gasoline I ad one part by volume of para-cymene and thus obtain a satisfactory anti-knock fuel. Paracymene is about twice as effective as benzol in producing an anti-knock fuel and possesses the particularly desirable feature that its boiling point lies at 17 5180 0., thus making it possible to use in admixture with paracymene anti-knock compounds of low boiling point, for instance, benzol, if para-cymene cannot be obtained in suflicient quantities or if its price should become higher than that of the low boiling compounds. It possesses the further highly advantageous characteristic of having its freezing point at 73.5 0.,

which makes it particularly suitable for admixture with gasoline intended for use at very low temperatures, such, for instance, as

are encountered in flying. The exact proportion of para-cymene to gasoline will depend upon the particular quality of gasoline used. The proportion which I have 'ven is suitable for what is known as Pennsy Vania gasoline. The roportion of para-cymene may be reduce if care is taken to avoid elimination,

as far as possible, during the distillation 1929. Serial No. 378,582.

process, of unsaturated hydrocarbons present in the sulfite spruce turpentine. The exact proportion of the para-cymene, whether used alone or in admixture with other anti-knock compounds, may readily be determined by varying the proportions and by test determiningwhich proportion produces a satisfactory anti-knock fuel. Of course, in determining the proper proportion the conditions under which the fuel is to be used, for instance, the degree of compression in the engine, may have to be taken into consideration.

Instead of para-cymene I may use one or more derivatives of para-cymene, for instance, Q-amino cymene prepared from paracymene by a well known process of nitration and subsequent reduction. After such nitration and reduction the final product may contain a substantial amount of 3-amino cymene, that is to say,-may consist of a mixture 7 of 2-amino cymene and 3-amino cymene. This mixture, or 2-amino cymene alone, is about 85% as effective as anilin, that is to say, a satisfactory anti-knock fuel can be obtained by adding to 16 parts by volume of Pennsylvania gasoline 1 part by volume of such mixture or substance. Of course, the proportion of this mixture or substance may be reduced if benzol or some other anti-knock compound is added to the gasoline. The advantage of using 2-amino cymene is that it is soluble in gasoline in all proportions, whereas anilin is soluble in gasoline only to the extent of 7% by volume. I may also, if desired, use as the, anti-knock compound sulfite spruce or balsam turpentine from which sulfur dioxide gas, acids and pitch have been removed but from which the unsaturated compounds naturally present have not been removed.

When in my claim I refer to para-cymene I intend to include in such expression as equivalents 2-amino cymene, 3-amino cymene and sulfite spruce turpentine or sulfite balsam turpentine from which acids, pitch and 95 sulfur dioxide gas have been removed or any other derivative of para-cymene which is useful as an anti-knock compound, all of Which act in a manner equivalent to paracymene as an anti-knock ingredient;' and 1 0 when I refer to spruce turpentine I intend to include as an equivalent, balsam turpentine. 1

I claim:

As an anti-knock fuel suitable for use in internal combustion engines, a mixture of gasoline and para-cymene, the latter substance being present in a proportion of more than 2% by volume of the total mixture.

FRANK E. L. BUSCH. 

